clauseh



I H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATIOh FILED APR. 13! 1918.

//1 Van for. flew/y f. 6/41/58.

Patented A11 12, 1919,

Affy HENRY P. CLAUSEN, OI? MOUNT V ERNON, Z'IEW' YDRK, ASSIGNDR 1'0WVEfiTEEN ELECTRIC COMPANY, tnoonroznirnn, or new ren n. Y.,

TELEPHONE-EXCHANGE SYSTEM;

Application filednptil 13, 1912.

To all "to/tom may concern l3: it known that l, Hnnnf: P. CLAUSEX, acitizen of the United States; residing'at Mount vernon, in the county ofli'estchester, State of New York. have invented certain new and usefulImprovements in Telephone l-lxchangc S i stems, of which the followingisa full, clear, concise, and exact description.

This in 'ention relates to telephone exchange systems employingautomatic switching mechanism controlled from the sub s ribcrs"Substations for establishii'ig connections.

The object of the invention is the :provision of a system ctnnprisingcircuits and apparatus arranged to be controlled from the subscribersconic eit'ectivc after a connection has been e tablished over a train ofS\\'li'(l1('.;-3 from one suhacribcfs line to another, ond train oiswitches under one of the subscribers. Such subscriber may thereuponcause the operation of the second train oi..'\\"itchcs in accordancewith the number of a dcsircd third party, to bring thc third party intothe connection. while at the same time the originally establishedconnection is maintained intact and intertercnce by other subscribersprevented by the application of the usual busy condition to each of theseveral lines con'erned in the conv irsational connect-ion.

More particularly there is contemplated a system in which. aconi'icction'having been built up over a series of switches from acalling to :1 called sulmcribcrs line the called subscriber maythereupon, manipulate his sender to cause the extension of theconversational connection over a second s ries of switches to the lineof a third subscriber.

A feature consists in the provision of a special auton'iaticallyoperated hunting switch associated with the final or connector switch,and arranged that. after the connector has completed the connection fromthe calling line to the called line. a series of impulses transmittedfrom the called substation to the connector tch serves to initiate theoperation of said special switch. Th'ej'special switch has appearing inits terminal bank the terminals or" circuits leading to first selectorswitches, and when thus set in (meration by theralled subscriber itautomatically operates to find the to place a secthe control oi:

Specification of Letters Patent.

substations and which nia be- Patented Ang.-. i2,

Serial Ho. $28.39-

ten-ding the talking conductors of the established connection to an idlefirst selector trunk. The called subscriber may then send inipuleeg fromhis station directly to the first selector switch to operate the same.and to subsequently actuate the requisite number of succeeding switchesto finally in clude the telephone line of a. desired third party in theconrersatitmal connection previously established between himself and thecalling subscriber.

Q! .t .i 3| 7 .ulltll o her feature; as ale contemplateu by the presentinvention will appear from. a ctnlsidcration of the followingdescription.

In the drawing the figure shows a portion of an automatic telephonesystem comprising the telephone lines and substations of threesubscribers, together with the circuits and switching mechanism employedtot-ting connections between said lines in ac cordance with theprincigles of the invention.

lirictiy stated, there is shown a subscribefis substation A consistingof the usual apparatus and the lines of which terminate at the exchane'ein. a preliminaryswitch (not shown) such as a line or finder switch. Thesubstation A is also provlded with an unany number of selectors may beincluded in the train of switches intermediate of the calling line andthe connector. The circuits and apparatus of one of the connectorswitches C are shown in detail in the lower portion ofthe drawing andinclude a line relay 8, operating magnets 9 and 10, and movable brushes11, 12, 13. The brushes 11, 12, are arranged to be dircctirely operatedin two separate movewith the multiple terof telephone lines, theterminals or". one of these lines. such as that associated withsubstation 3. being shown at l-l. 15. 16. A- ociated with the connectorswitch is a special hunting switch S having brushes 17,

b n'iatzncts 9 and. 1G

in et- Gil , which may be constructed to operate e movementrotaryswitch, actuated step by means or a. stepping mag- The brushes 17,18, 19of the spe* ere arranged to cooperate with of circuits which are Associred with each of the L provided with one cl these special switches is asolenoid magnet 2-1 adapted to respond to the transmission of a specialseries of impulses from 21 called substation, as B, to initiate theoperation of the said special hunting switch S.

the upper right-hand portion of the drawing are shown in detail thecircuits and ug iparatus of another connector switch C" substantiallyidenticel in all respects to the connector already described. Thisswitch is provided with brushes 25, 26, 27 arranged to coiperute withthe terminals of telephone lines, and which are shown in operativerelation to the line of substation l). A detailed description will nowbe given of the ope-nation oi thesysteni embodying this invention,explaining first the manner in which a. call is extended from a callingto celled subscribcrs line, and then the manner in which a. secondconnection may be extended to the line of a third subscriber from theconnection already established. For tnis purpose, is assumed that theparty at sul'is'tation A desires to converse with the party atsubstation 13. Upon the removal of the receiver 31 from the switch-.

hook 32, the conductors and 34: or" the calling line are closed to causethe operation of a line or finder switch (not shown in the drawing) inthe well-known manner. The subscribernow manipulates his sender 1 todircctively control the operation of the first selector, and as manysucceeding selectors as may be involved, the actuation. of the last ofthese selectors 2, 3, 4 serving to extend the line 33, 34 by way ofterminals 6 and T to u connector switch C having access to the group oflines containing the called line ll. When the selector line brushes 3and t nmlre c' c'tion with terminals 6 and ,7, the following circuit isclosed for the euergimtion of the calling line relay 8 of connector C:buttery, through the upper windingof said relay, terminal 6, brush. 3,through the terminals and brushes preceding switches (not shown),conductor 33, over the loop of substation A, conductor 34:, through thelbrushes and switches preceding the selector 2, 3, 4, brush l, terminal'7, lower winding of rel uy S, to ground. The relay 8 by operating acircuit at its armature and front net for the slow relay 3-5. Relay estterminal 5 to connector SWltCll W i ,s A,

ie 56:13), 30 as its n in 1 ti busy to other s leading to firstselecterminals of lower armature and front cont-act also prepares a.stepping circuit for the transmission of impulses to the operatingmagnets as will presently be seen. The calling subscriber having thusextended his line through selector switches to the'connector C continuesto operate the sender l in accordance with the tens digit of the callednumber. For each interruption produced in the line by sender 1 in thetransmission of the tens impulses the line relay 8 retracts and attractsits armature. At the first retraction of the armature of relay 8, thefollowing circuit is closed to send an operating impulse to the primarystepping magnet 9: grounded armature and back contact of relay 8, lowerarmature and front contact of slow relay 35, winding of slow relay. 36,conductor 37, through the winding or magnet 9, side-switch arm 38 inposition 1, to bettery and ground. The magnet 9 energizesl and steps theconnector brushes 11,

12, '13 one step forward into operative relation to the first group ofline terminals in the tens series, the primary magnet 9 operates toadvance the brushes ll, 12, 13 forward one step, finally bringingthem torest in operative position relative to the tens roup of line terminalsincluding the termimils 14, 15, 16 of the line of the desired substationB. When the first impulse is sent over the albove traced circuit by thelinerslay 8, the relay 36 energizes, and being slow to release, retainsits armature in attracted position during the short interruptionsproduced by the stepping relay 8. Upon the encrgizatio-in of slow relay36, a circuit is established from battery, through the winding of escapemagnet 39, contact 40, armature of relay 36, to ground. The escapemagnet 39 being designed to move the 'side switch from position toposition on denergization, energizes preparatory to advancing said sideswitch into position 2. At the cessation of the impulses of the tensseries, and the consequent maintained. energization of the line relay 8,the circuit of slow relay 3% is held open for :1, sufficient period oftime to permit said relay to retract its armature and open the circuitof escape magnet 39. Said escape magnet. thereupon releases the sideswitch from first to second position. The connector switch is now incondition to receive the final or units series of impulses.

The calling subscriber by operating his sender 1 in accordance with theunits digit of the desired number causes the relay 8 as before toretract and attract its armature in correspondence to the number ofinterruptions produced in the calling line. On the first retraction oithe armature of relay 8, an impulse is trensu-iitted over the followingcircuit to the SCLClllaly' stepping magnetlil:

Lu e 'lllCl buclr contact of reand font contact of lay 36, conductor 87,armature and contact of relay il, the Wii'iding of magnet 10, side-- sarm 38 and its second position con- I to buttery. The nmgnet operates inresponse to the JlOSLlI'Q of this circuit and tops rho bri 7 i1, 12, 13onto the first set s in the selected group. At

.1?) lemon vl suceeec i ,5 ml; *ution of in, armature line relay 8responsive lo the units of line interruptions, stepping magner 10operates to advance rid brushes step by o er the-line terminals, undfinally as the cessation of said series lLlLGlll'iIO 'resi engagementwith the terminals 14-, 15 in 0 inc culled line. The slow relay :lie"rst denergizzition of v e beginning of the secondary "icnl of theswitch and remsins enerl during the fOll0'll1; short inter 'upesion or.the primary series of impulses.

, ,"1cstim1 of relay 36 again closes u cirr the operation of escapemagnet- 39 nutorg. 23o releasing the side switch end to third position.If the called rnisj-J, :1 ground poen iz1l is present on t ierniinsls16, having been applied V r o either from u side-switcl'i. arm simiir toarm l2 and its third position contact oilaer "rector switch, provided mebusy as u culled line, or from u finder l' i switch provided. the lineis busy as u l 'ne. Under this assumption, when ,7 reps its brushes 11,12 and o ierinin is 1%, l5 and 16 at the end of he one selec moremenl',and u suliicient period. of time nus elapsed to permitluedeenerg'izution of slow reluy36, u-ncw holding sill i. Riel l for escapemagnet 39 o rqc-bc'fore breuk Contact l0 before said ce'cnergize, due lollie severance II us; can

l'fifll'llj by the retraction of holding circuil; may be pole ofbuttery, through oi: escape mugi'iet mnlzecon ine!" l0, winding of rcluyi I 'de-switcli urm in its secwsition, test brush 13, to the groundedEscapev magnet 39 therefore lied and prevents the release it i: switchin-eo third position. He-

lay 41 energizes in the circuit just traced said at its lois'cr armatureand the malts i iii-- outset l3, clrrs n holding cirour: escape nnigzne'r. lrmn f magnet 9,

no winding :2

1g 01 relay ll, contact: c of said reluv, to ground prod e. by saidrelay 8 in the .mzm- *SCI'EUQCl in connechon with tlietrunss toconductor 64, which bus tone is induc.'

lively transmitted in the well-known mun nor to the substation apps ntusof the calling line. The culling party being thus informed that thedesired line is busy replaces his receiver on the switclihook, therebycuus- .ing the denergizution of the connector line relay 8. Relay 8 onretracting its iii-nurture permanently opens the circuit of slow rcluy35, which in turn deencrgizes and completes the following circuit forthe connector rc- -lcase magnet 47: buttery, through the winding ofmagnet 47, primary off-normal contact 48, back contact and lowerarmature of relay 35, buck COIIl'iLCt and armature of relay to ground.The release magnet energizes and restores the connector switch C to itsnormal position. lVllcn the switch is completely restored the primaryoff-normal -contact is again opened, thereby opening the, circuit ofmagnet 47 umuew the some to deencrgize. The slow reluy on releasing alsoremoves at its upper iii-mature the busy ground from the selectortesterminal 5. The removal of this ground potential from terminal 5 mayopcrnte, as is well known, to

cause The restoration of the selector switches reaching third position.places u busy ground on the test-terminal 16 of tlio -nllcd line, andalso closes n circuit for relay 45), which ulstrncts its arnuu'ures toconnect the talking conductors 50 and 51 through to brushes l1 and 12respectively. The circuit for l'QiZi 49 is traceable from buttery,through the winding of such relay. contuct and outer arnniture of relayilllllill'llle and conflict of escape nuzgnc' 2-35.), iuncr :u-umrurcand contuctof relay side-su'ilclr arm 42 in position 3, to ground. Willithe side switch in this position, o circuit is also closed us followsfor the ringing relny 53: frec'pole of battery, sidc-switcl1 arm 38,conductor 54, upper armature and contact of rii'iging cutoff relay 55,through the winding" of relay 53, interrupter 56, to ground. Theinterrupter 56 operates to interiniltenl'ly onerund dci nergrizc therelay 53. which by 1 corresponding :ittrnciion and rclruction of itsnrniuturcsintcrinittcnl'ly applies the ringing source of currentindicated at 57 to {be willed line. The ringing circuii may be tracedfrom source 57, "from coniictand outer nrnuiture of relay 53, conductor51, inner nrnmture and contact of relay 4-9,

. which, after a talkino connection mg of relay 58,

armature and contact of relay brush 12, terrninal 15, over the loop ofcalled substation B, including-the ringer thereof,

terminal 1%, brush 11, contact and upper arinature of relay 49,conductor 50, to ground at the inner armature and front contact of relay53. When the called sl'lbscriber removes his receiver, and during; theperiod of operation or interrupter 56 that the armatures of relay areretracted, a circuit is established as follows for. the called linerelay 58: battery, through the upper Windconductor 59, contact andleft-hand armature of slow relay 60, lefthand armature and back contacto:t' slow relay 61, closed contact of solenoid magnet 24, conductor 63',back contact and outer armature of relay 53, conductor 51, inner 4:9,brush 12, terminal 15, over the loop of substation B, terminal ill,brush. 11, contact and upper armature of relay 419, conductor 50, innerarmature and back contact of relay 53, contact and right-hand armatureof relay (30,

conductor 84, through the lower winding of relay 58, to ground. Thecalled line relay 58 on energizing closes a circuit for the ringingcutoff relay from battery, side-switch arm, 38, conductor 54, throughthe Winding of relay 55, conductor 65, lower armature and contact ofrelay 58, to ground at the off-normal contact 66. Relay 5-5 at its upperarmature opens the circuit of ringing relay 53 to discontinue theringing op'eratiom'and atits lower armature closes a locking circuit foritself independent oi relay 58. Theilines of the calling substation Aand called substation B are now connected through for conversation,talking battery current being fed to the calling line through thewindings of relay 8, and to the called line through the windings ofrelayv 58. ..Condensers 67 and 68 inserted in the talking conductorsserve to coni'lucti ely separate the calling and called lines. versationthe calling party by replacing his receiver to the switch hook causesthe restoration of the established connection as has been explainedhcreinbeforc.

After a calling subscriber, as A, has cornplcted the extension of atelephone connec tion between his line and that ol a called subscriber,as B, in the manner above described, it may be desirable, due to theinability of the called subscriber to give the calling party the fullinformation required, or for other reasons, to bring a third subseribersline into talking relation to the already esta-hhshed connection. Thecase will now be assumed in has been built up between th llinesjt andid, it is desired to include the line D .in the conversa tional circuit.To attain this end it is only necessary for the called subscriber at B,While holding his receiver on the hook, to

manipulate the sender 35) to transmit to the sion of the desired tive incontrolling the to conductor closes a circuit for the magnet 24 frombattery, through the winch ductor 72.

cluding the At the close of the con-- sufiiciently to open contact 2,relay for slow relay grounded outer connector C: first, a special seriesof impulses which are effective to operate the switch S5 to prepare theWay for the exteneonnection over second train of switches; and.thereailt "l. series of selective impulses Wlswitches or" said train..l. special ser1es oi": impulses ma operating the sender sointerruptions, for exam ple, in of substation Since as ace the calledline, relay 58 is now ."gizetl in series with the called line, eachinterruption in such line causes th relay 5% to retract and attract itsarinatures ccrrespcudi ly. upper armature of line relay is to coiiperatewith aniahc-before-bre: tact 70 in such manner that said cor is inengagement with its grounded 71 for a. briei interval during bothneretracting and attracting movements of the armature of relay 58.Hence, the relay 58 operates in response to the-ten successiveinterruptions produced by sender 6. the ten successive deiinergizationsand energizetions of. said relay result in twenty l!lGlTL-;ll taryground connections being; applied to the conductor 72.. he applicationof. ground solenoid ing; of said magnet, to the grounded con- Solcnoid12% is constructed such that the receipt of the twenty impulsesproducedby the operation of relay 53 is Smilicient to attract itsplunger 73 to a position Where it becomes effective to open the contact6 It will be noted at this point that the winding of slow relay 61, andthe path inleft-hand armature and heel; contact of relay 6]. and contact62, in parallel with each other, both being in rics with conductors Tiand 63, which c nductors comprise a part of the above traced circuit forline relay 5S. Normally then, the relay 61 remains inert, being shuntedout by the low resistance path through contact But when solenoid2iatt-racts its plunger energizcs and completes the following handarmature and frontcontact of 61, through the Windingof relay $0,right-haiul armature and contact of 61, contact 75, conductor 76, Windinof slow relay 77, to battery. Relays ant. .77 both energize in thiscircuit. The attraction of the armatures of relay 6!) opens circuit ofline relay 58 and slow. relay 61. becomes deenergized, but the relay 61is so adjusted as to retain its arinatures attracted until the quickacting; switch 8 has had time to step brushes ill, l8, 19 over the en erow of truult terminals 21, The sei'cl S 1. vi tne pro e-r the huntingperiod of has no normal position, but is adapted when not busy to steedwith its brushes 17 18, 19 upon the terminals of the selector, such asthe selector indicated at 78, 79, 80, last used in the extension of :iconnection. It then the selector upon the trunk terminals 21, :22, 28,0fwhich the switch 55 is standing, is busy y reason 01 having been takenfor use in the extension of a cal scriber in. the system, a ground willhe present on the test terminal 23 of the switch S. This ground mayeither front contact of the first slow relay of selector 78, 79, as isWell known or from the front contact of the first slow relay at theconnector switch, as the relay 35 of conneci'or C and re. 81 oilconnmtor L. Therefore, on the encrgizution of relay 7? uhoi'e dcscribed,a circuit is closed as follows for the stepping magnet 20 of specialswitch but side-suite- 38 in third position,

' i wi: ling of in contact thereof, on 1 ure relay 7?, bee-5 inner lowerarmature of relay erouiulcd terminal and opens own ance the brushes ll,18 I inuls of trunks leuclin rut selectors, until the terminals in,trunk l ading to an idle se 1 reached. llhen -.i.'cluy the circuit ofinuggnet thcreii'i'rh nus also winding1 oi 1 re-- :1 i V L r 1 mature3.310. contact J V estnolish relay luy is set i from open 28 .1 1e timethat magnet is stepping test brush 19 over grounded terminals. But whenthe non-grounded terruins-.1 is reached, suliicient current flows torelay 83 to cause its encrgizution. The stepping magnet 20 is includedin series with relay 83, but the resistance of relay 83 being so highsaid magnet does not energize. The operation of relay 83 completes acircuit from battery, through the Winding of the line relay (not shown)of the first selector 78, 79, 80, terminal 21", brush 3?, contact andinner upper armature of relay conductor 8%,

eel: Contact and inner urniuture of relay conductor 50, and thence overthe called line B as before traced, returning by conductor 51, outerarmature and hook contact of relay 53, conductor 63, winding of slowrelay (S1, left-hand armature. and front contact thereof, conductor 85,middle lower armature and contact of relay 83, brush l8, terminal 22, toground through the other Winding of the selector line relay (not shown).which held its flllnlillul'GS attracted during switch 8. end while itscircuit Was maintained opened by relay 60, is again energized in thecircuit aho ve traced.

l by some other sub-- be derived from a.

' front contact Relay G1;

ill

The attraction of the upper armature of re lay 83 closes a substitutecircuit for slow relay (S0 to replace the one )rcvi.)usly described. Theuttruction of the inner lower urnuiture of relay 83 closes a holdingcircuit for said relay in place of its original circuit. which isSO-VGI'QIl by the ilei ncrgizution of slow relay 7'? shortly after theopening of Contact 75. lhiscircuit uury be traced from battery,side-switch arm 38, conductor 82, winding, armature and contact ofmagnet 20. Winding, front contact and inner lower a1 nurture of relay83, test hrush 19, to the test terminal 23 which has been grounded uponthe seizure of selector 78, 79, SO in the wellknown niaiin The line oithe first culled substation ll has now been extended liy Wu: 0'! thehunting switch S to u lirst selector nll'lllfll TR. 79, R0. Thesubscriber on operuting his dial (Bi u= suid selector to more inioengagement .1 terminals S6 87, lending to the connector C which in turnhas access to the desired line D. (in the seizure oil the connector C ucircuit is completed for line relay 85) as follows: buttery, through theupper windingoi relay 8 terminal 66, brush TS, termiuul 21, brush 1?,contact and inner upper lll'll'lilllllfi of relay 83. conductor contactand inner 53., conductor 50, contact of ml 14, over upper rcluy l9.brush ll. the loop of substation l6. sh l2, routucl; and lower ur-,cenducmr 5] outer urniuontuct o'l' relay 53, conductor 5i. lellalmudarmature i act of said relay til. iniddlc nature i lcontmtolrelay1'3.brush l8, terminal hrush 79, terminal lower Winding: of role 39. toground. Reluv 89 thus becomes energized in series with the first culledline B, and closes u circuit for slow relay 81. Which places u ground atits ower urinature on test Wire 30 to render the switch C busy, and ulsoto hold the circuit closed for relay 83 us uhove explained. Thesubscriber no operutes sender (3!) to send the tens and units impulsesto the connector ln response to the tens series rela 80 vibrates itsarmature and at each refraction. a circuit closed as follows lmprin'mrxstepping magnet 90: grounded ouch Contact of relay 8!),

armature and inner armature mid of relay S1, wincin of slow relay '91,Winding of magnet 90, side-switch arm 92. to huttr 3 he escape magnetSit-B is energized as Well understood and at the end of the tens impul.u'ics' releases the side switch into second position. In response to theunits impulses the following circuit: is closed for the secondarystepping magnet 9i: grounded armature and back contuct of reley 89,inner urnuiture and frontcontact of relay 8]., Winding of relay ill.lelehzmd armature and contact of relay 95, through the winding of magnet94-, side-switch arm 92 in second position,-to battery. Magnet 94operates in this circuit to, advance brushes 25, 26, 27 over the groupand into engagement with the terminals of thGSSGCOHCl called line D.Assuming line D to be idle, escape magnet 93 deenergizes at the end ofthe final series and steps the, side switch into third position. In thisposition of the side switch the ringing relay 96 isintermittently-actuated to apply ringing current to the called line inamanner similar to that described in connection with connector C. \Vhenthe subscriber at substation D responds the called line relay 97energizes, thereby causing the ringing operation to-cease as already ex-.plained.

The telephone line of the third party at D has thus been included in theconnection and all three subscribers may converse with one another.Talking battery current is fed to the substation A through the windingsof the calling line relay 8 of connector C, as in the case when theestablished connection involved only the calling and first calledsubscribers. But the first called substation B is now supplied. withtalking current through the windings of the calling line relay 89 of theconnector 0 instead of the called line relay 58 of connector C. Thesecond called substation D receives battery current from relay 970iconnector switch C. The conversational circuit between lines A and B isconductively separated by condensers 67, 98 and 68, 99; theconversational circuit be tween lines A and'D by condensers '67, 98, 100and68, 99, 101; while that between lines B and D is separated bycondensers 100 and 101.

At the completion of conversation, the calling party atA'hangs up hisreceiver to efi'ect a release of connector C and the remaining switchesin the t ain interconnect- 'ing his line with that ofsubstation B,-ashas already been set forth. When brushes 11,

. 12, 13 of connector C break engagement with the terminals of thecalled line B, the hereinbefore traced circuit of relay 89 is severed,thereby resulting in the release thereof. Retraction of relay 89 causesthe deenergization of relay 81; which completes the following circuitfor release magnet 1020f connector C: battery, through the winding ofmagnet 102, primary off-normal contact 103, back contact and armaturesof relays 81 and 89 to ground. The connector switch C is thereuponrestored to its normal position. The selector switches preceedingconnector C are likewise released at this time.

What is claimed is: 1. In a telephone system, a calling line, a calledline, means for establishing a connection between said lines, a thirdline,

' an automatically operated hunting switch,

aeiarre means controlled by the called subscriber for initiating thehuntingmovement of said hunting switch to extend the establishedconnection in the direction of the third l and means controlled by thecalleds scriber for completing the extension of the establishedeonnectionto said third line.

2. In a telepl'n'me system, a calling line. a called line, selector andconnector switches for establishing a connection between said lines, athird line, an automatic step-bystep hunting switch individual to saideonnectors, means controlled by the called subscriber for initiating thehunting movement of said hunting switch to extend the establishedconnection in the direction of the third line, and means controlled bythe called subscriber "for further extend n the established connectionto said third line.

3. In a telephone system a calling line, a called line, sending devicesassociated v: said lines, means including selector and connectorswitches for establishing a coin nection between said lines, a thirdline, an automatiuilly operated hunting switch.

means controlled by the called subscribers sending device for startingthe huntii'ig movement of said hunting switch to extend the establishedconnection to an idle selector switch, and means controlled by thecalled subscribefis sending device for operat a said selector andsucceeding swit s further extend the established conn ion to said thirdline. i

. at. In a telephone system, a calling line, a called line, impulsesenders associated with said lines, means including selector and con- 5.In a telephone system, a calling line, a

called line, an impulse sendenassociated witi the called line, a train.of automatic switches, means for operating said switch s to establish aconnection between said li 3s, a third line, an autonnitically operatedhunt ing switch, a second train of automatic switches, anelectromagnetic device and means including said sender for transmittingimpulses thereto, said device responsive to a predetermined number ofimpulses start the hunting movement of: said hunting switch-to extendthe established ccnnec to said second train of switches, and meanscontrolled by said sender for operating said second train of switches tofurther extend the established connection to said third line.

In a telephone system, a calling line, a called line, an impulse senderassociated with the called line, a train of automatic switches, meansfor operating said switches to establish atalking connection betweensaid lines, an automatically operated hunting switch associated with thelast switch of said train, a third line, a second train of automaticswitches, means controlled by said sender for initiating the huntingmovement of said hunting switch to extend said talking connection to thesecond train of switches, and means controlled by said sender for oeratin said second train of b switches to further extend the nection tosaid third line.

In a telephone system, a calling line, a called line, means forestablishing a connection between said lines, a third line, a pluralityof trains of automatic switches arranged to extend said establishedconnection to the third line, an automatically operated auxiliary switcharranged to test the talking concondition of the first switch in each ofsaid trains of switches, means controlled by the called subscriber forstarting the testing operation of said auxiliary switch to select atrain of switches, and means for operating the switches of theselectedtrain to include I said third line in the establishedconnection. 8. In a telephone system, a calling line, a called line,impulse senders associated with said lines, a train of automaticswitches,

I means controlled by the calling subscribers sender for operating saidswitches to estab lish a talking connection between said lines, a thirdline, a automatic switc es adapted to extend said talking connection tothe third line, an ad; tomatic auxiliary switch arranged to test andselect the first switch in each of said plurality of trams of switches,an electrolurality of other trains of magnetic impulse device andcircuits con trolled thereby, means including the called subscriberssender for transmitting impulses thereto, said device being responsiveto a definite number of impulses only to control said circuits toinitiate the testing movement of said auxiliary switch whereby a talkingconnection.

In witness whereof I hereunto subscribe my name this 3rd day of April,A. D., 1918.

HENRY P. CLAUSEN.

